A negative return value doesn't make sense for any of those functions.
The return types were inherited from POSIX, where they also need to have
an indicator for an error (negative values).
This is to differentiate between the upcoming `AllocatingMemoryStream`,
which automatically allocates memory as needed instead of operating on a
static memory area.
Error::from_string_literal now takes direct char const*s, while
Error::from_string_view does what Error::from_string_literal used to do:
taking StringViews. This change will remove the need to insert `sv`
after error strings when returning string literal errors once
StringView(char const*) is removed.
No functional changes.
A mistake I've repeatedly made is along these lines:
```c++
auto nread = TRY(source_file->read(buffer));
TRY(destination_file->write(buffer));
```
It's a little clunky to have to create a Bytes or StringView from the
buffer's data pointer and the nread, and easy to forget and just use
the buffer. So, this patch changes the read() function to return a
Bytes of the data that were just read.
The other read_foo() methods will be modified in the same way in
subsequent commits.
Fixes#13687
MemoryStream is the Core::Stream API's streamlike access to a chunk of
memory, mimicking AK::DuplexMemoryStream. The implementation is very
similar, except that no APIs except the SeekableStream operations
currently exist. This will be fine for the first users and can be
expanded upon later.
